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76 Cards in this Set
- Front
- Back
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The three tunics (layers) of the eye |
Fibrous (sclera and cornea), Vascular (iris, choroid, cilliary body), Nervous (retina) |
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Fibrous Tunic |
Sclera and Cornea |
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Vascular Tunic |
Iris, Choroid, Cilliary Body. Responsible for nourishment |
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Nervous Tunic |
Retina. Contains rods and cones |
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Rods and Cones |
Located in the nervous tunic or neural layer of the retina. Cones see color. |
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Macula |
Where light will focus in a healthy eye. Contains 120 million rods and 6 million cones. |
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Fovea |
Center of the macula. Contains the highest concentration of cones. |
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Optic disc |
The point where the optic nerve enters the eye. Contains no photoreceptor cells. Known as the "blind spot" |
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The three fluid filled chambers of the eye |
Anterior (between cornea & iris), Posterior (between iris & lens), Vitreous (between retina & lens) |
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Anterior Chamber |
Between cornea & iris. Contains aqueous humor produced by the cilliary body. |
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Posterior Chamber |
Between Iris & Lens. Contains aqueous humor produced by the cilliary body. |
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Vitreous Chamber |
Between Retina & Lens. Contains Vitreous humor which maintains the shape of the eye. |
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Aqueous Humor |
Watery fluid produced by the cilliary body. Found within the anterior (between cornea and iris) and posterior (between iris and lens) chambers of the eye. Maintains intraocular pressure (IOP) Provides nutrients to the lens and cornea. Continually drained from the eye through the canal of schlemm. |
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Vitreous Humor |
Thicker gel like substance which maintains the shape of the eye. Found within the vitreous chamber (between the retina and lens) |
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Cornea |
Transparent dome shaped structure, consisting of five distinct layers, where light enters the eye. |
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Five layers of the cornea |
•Epithelium (Outermost layer, rests on Bowman's Membrane) •Bowman's Membrane (Protective Barrier) •Stroma (Makes up 90% of the thickness of the cornea) •Descemet's Membrane(Separates the Stroma and the Endothelium) •Endothelium (Innermost layer, removes water from the cornea, helps to keep the cornea clear) |
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Epithelium |
Outermost layer of the cornea, rests on Bowman's Membrane |
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Bowman's Membrane |
Located between the Epithelium and the Stroma. Acts as a protective barrier. |
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Stroma |
Located between Bowman's Membrane and Descemet's Membrane. Makes up 90% of the thickness of the cornea) |
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Descemet's Membrane |
Separates the Stroma and the Endothelium. |
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Endothelium |
Innermost layer of the cornea, removes water from the cornea, helps to keep the cornea clear |
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Iris |
The colored part of the eye that controls the amount of light that enters the eye through the pupil. Is controlled by two muscles, the dilator (opens) & the sphincter (closes). Has the ability to change the pupil size from 2mm to 8mm. |
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Two muscles that control the Iris |
•Dilator (opens, allows more light in) •Sphincter (closes) |
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Dilator |
One of the two muscles that controls the iris. Opens the iris to allow more light into the pupil. |
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Sphincter |
One of the two muscles that controls the iris. Closes the iris to restrict the amount of light entering the pupil. |
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Crystalline Lens |
Focuses light on the retina. |
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Accommodation |
The process of focusing on objects based on their distance. Is achieved with help from the ciliary body. |
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Ciliary body |
•Surrounds the crystalline lens •Is attached to the crystalline lens via fibrous strands called zonules •Helps with accommodation |
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Zonules |
Fibrous stands which attach the ciliary body to the crystalline lens |
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Focusing up close |
Ciliary body contracts, zonules relax, crystalline lens thickens adding power |
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Focusing at a distance |
Ciliary body relaxes, zonules contract, crystalline lens is drawn outward making the lens thinner allowing the eye to focus at a distance |
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Palpebrae |
Another term for the eyelid |
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Medial canthus |
The point where the upper and lower eyelids meet near the nose |
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Lateral canthus |
The point where the upper and lower eyelids meet towards your ear |
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Eyelashes |
Strong hairs that run along the upper and lower palpebral margins. They filter debris from entering the eye |
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Meibomian Glands |
•Located along the inner margin of the eyelids. •Secrete a liquid that keeps the eyelid from sticking together. •Secretions are part of the tear film |
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Fornix |
•Located behind the eyelid or palpebra and along the sclera •It is where the two layers of the conjunctiva meet & join |
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Lacrimal Gland |
•Inside the orbit of the eye •Produces the bulk of the tears •Located above the lateral canthus in a depression in the bone that surrounds the eye. |
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Lacrimal Puncta |
•Small openings (pores) located at the medial canthus •Allows the accumulated tears to drain off the eye. •Tears drain through the nasal cavity |
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Lacrimal Canals |
The path the tears take from the eye, to the lacrimal sac, and then to the nasal passage |
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Lacrimal Caruncle |
Located at the medial canthus produces a liquid that soothes and lubricates the eye. Combines with secretions from the meibomian glands to make up the eyes tear film. |
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Cornea |
Clear structure that covers the iris. The first major structure that refracts light as it enters the eye. Has no blood supply, gets all of its oxygen directly from the air. |
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Pupil |
The opening created by the iris changing size. |
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Sclera |
The "whites of the eyes" Thick, tough, fibrous layer that provides the structure of the entire eyeball. |
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Limbus |
Where the cornea blends into the sclera. |
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Iris |
The colored area under the cornea that opens and closes to regulate the amount of light entering the eye |
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The Oculormotor Muscles of the Eye |
•Lateral Rectus •Superior Rectus •Medial Rectus •Inferior Rectus •Inferior Oblique •Superior Oblique |
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Lateral Rectus |
•One of the oculormotor muscles of the eye. •Rotates the eye laterally or out towards the ear. •Attaches directly to the side of the eye and runs straight back. |
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Superior Rectus |
•One of the oculormotor muscles of the eye •Eye looks up •Attaches directly to the top of the eye and runs straight back |
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Medial Rectus |
•One of the ocularmotor muscles of the eye •Rotates the eye medially or in towards the nose •Attaches directly to the side of the eye and runs straight back |
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Inferior Rectus |
•One of the oculormotor muscles of the eye •Eye looks down. •Attaches directly to the bottom of the eye and runs straight back. |
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Inferior Oblique |
•One of the oculormotor muscles of the eye •Eye rolls, looks up and to the side. •Attaches along the lateral side of the eye and runs under the eye passing over the inferior rectus and attaches medially. |
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Superior Oblique |
•One of the oculormotor muscles of the eye •Eye rolls, looks down and to the side. •Attaches under the superior rectus passes through a bony spur known as the Trochlea and then follows the path of the superior rectus. •The raised attachment point provides the ability to give the eye rotation. |
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Trochlea |
•Bony Spur •A raised attachment point which gives the superior oblique the ability to give the eye rotation. |
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The Emmetropic Eye |
Light focuses directly on the retina without the use of corrective lenses |
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Refractive Errors |
•Eight Common Errors •Presbyopia •Simple Myopia •Simple Hyperopia •Simple Myopic Astigmatism •Simple Hyperopic Astigmatism •Compound Myopic Astigmatism •Compound Hyperopic Astigmatism •Mixed Astigmatism |
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Formula for a diopter |
D=1/f f=1/D D=Power in Diopters f=Focal length in meters |
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Presbyopia |
Crystalline lens can no longer change shape and provide accommodation |
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Simple Myopia |
All rays of light focus at a single point in front of the retina. Corrected with minus lenses Prescription example: -2.50 sph |
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Minus Lenses |
Cause light to diverge Corrects myopia |
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Simple Hyperopia |
All rays of light focus in a single point behind the retina Corrected with plus lenses Prescription example: +2.50 sph |
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Plus Lenses |
Cause light to converge Corrects Hyperopia |
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Simple Myopic Astigmatism |
Light focuses at two points, one on the retina and one in front of the retina. Prescription example: Plano -1.00 x180 -1.00 +1.00 x090 |
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Simple hyperopic astigmatism |
Light focuses at two points one on the retina and one behind the retina. Prescription example Plano +2.50 x045 +2.50 -2.50 x135 |
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Compound Myopic Astigmatism |
Light comes to a focus at two points, both in front of the retina. Prescription Example: -3.50 -1.75 x060 -5.25 +1.75 x150 |
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Compound Hyperopic Astigmatism |
Light comes to a focus at two points, both behind the retina. Example Prescription: +1.25 +.50 x030 +1.75 -.50 x120 |
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Mixed Astigmatism |
Light comes to a focus at two points, one behind the retina and one in front of the retina. Example Prescription: +.75 -1.00 x045 -.25 +1.00 x135 |
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Speed of Light |
186,000 miles per second |
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Nanometers |
One billionth of a meter |
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Wavelengths of the visible spectrum |
400nm to 700nm Violet is at the short end, Red is at the long end. |
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Ultraviolet (UV) |
Below 400nm |
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Infrared (IR) |
Above 750nm |
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Refraction |
A change in the direction of light as it changes speeds while passing through various transparent media. |
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Index of Refraction |
Notated as "n" Tells us how much a given material will slow down and change the direction of a ray of light passing through it. Common indexes of Refraction 1.498, 1.523, 1.586, 1.60, 1.67, 1.74 |
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Vogel's Rule |
•Plus RX Base Curve = Spherical Equivalent + 6.00 D •Minus RX Base Curve = 1/2 Spherical Equivalent + 6.00 D |
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Spherical Equivalent |
1/2 Cylinder Power + Sphere Power |
